Check the Grumble archives for plenty of threads on PPFA and the CPF program.
Cliff's right. PPFA has a Study Guide that leads you to everything you need to know. Check with PPFA or your nearest chapter for dates & places.
One caution: Don't take the exam without studying everything in the Guide. A lot of veteran framers take the exam without studying, thinking their years of shop experience will carry them through. But that is generally incorrect.
The CPF exam is heavy on preservation framing, and most self-taught framers don't get enough of that knowledge unless they really work at it. So if you really work at it, and you should be OK.